Full range fuses have been used for some time in transformer applications. However, these fuses generally could not be immersed in the transformer's oil. In order for the fuse to be immersible in oil, the oil seal provided by the end cap must maintain an absolute seal for the life of the fuse under oil (typically 20 years). This oil has an extreme temperature range of -30.degree. C. to a maximum of 140.degree. C.